Personal color pallette... -> is this possible?

Hi, I want to break an image down into a core group of colors. Is there any way in photoshop cs to define my colors so when I select one it snaps to the best choice...

I.E. if you select a color with the eye dropper then you check the RGB value of it you can click the "Web Only Colors" and it will snap to the closest choice.

I want to have a pallette of 10-11 colors and have it snap to the best choice...

Any ideas?

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2.

Or even better... take a whole image and convert it to the 10-11 colors I want. Is this possible with some sort of filter?

WHITE
BLACK
BLUE
GREEN
PINK
BROWN,
ETC
ETC

You can do that in Photoshop now. Its the closest way i know how to do it, maybe there is any other way to do it.
Just goto File -> save for web, and choose .gif for the file format.
Then you can choose the amount of colors, check the color table to lock the colors you want, and use the eyedropper tool there to point out the color. Then you can scale down the amount of colors you desire.

Hope this helped ;)